Design

When Quality, Security Count

By Sid Sidner, April 24, 2010

Static code analysis can make a big difference

Sid Sidner is director of security engineering for ACI Worldwide.

ACI Worldwide is a provider of payments software to banks and merchants around the world. With more than 800 software engineers working in development centers in seven time zones, issues such as software quality and security are critical to ACI's success. As director of security engineering, its my job to ensure that our code base is bug-free and intruder resistant, while continually improving the software's overall quality. These concerns aren't new. They've been our mantra since the company was founded more than three decades ago. We decided several years ago that the best way to ensure quality and security was to introduce static source code analysis into our development processes.

Static code analysis is the process of examining and evaluating software without actually executing the code. Analyzing software when executing software is known as dynamic analysis. Static code analysis is all about moving the detection of critical security and quality problems upstream, ensuring they're identified and fixed early in the development process.

This approach yields significant productivity gains across the entire process and leads to cleaner, more stable builds, more efficient testing, and of a course, a higher quality product. Besides helping us find bugs that we've missed in unit testing, static code analysis has made all our engineers aware of security issues and helped us teach junior staff better coding techniques.

What's Involved

Static source code analysis tools are almost entirely automated. They're like compilers, but instead of generating machine-executable code, they simply find bugs and issue warnings about security vulnerabilities, logic errors, implementation defects, concurrency violations, boundary conditions, and other glitches in the code. The tools provide a list of problems, each tied to a specific location in the source code. Detailed context is usually provided to explain how the tool arrived at the conclusion.

Static analysis tools use very sophisticated process flow and data flow analysis. The quality and security issues they identify are often complex and involve obscure logic problems, which is why these tools can be so valuable.

Static source code analysis tools analyze 100% of the source code, far more than any external test tools. For organizations that must comply with the Payment Card Industry Data Security Standard (PCI DSS) or Payment Application Data Security Standard (PCI PADSS), these tools fulfill code review requirement. They also produce valuable metrics, including kilo-lines of code (KLoCs), file counts, and "churn" -- that is, the number of files that have changed between two regular builds.

Introducing static code analysis and the requisite tools into the development process isn't always painless, however. At ACI Worldwide, we found many subtle pitfalls in our efforts to roll out this approach company-wide. The tool changes the way many people work and must become a part of the organization and its culture.

For instance, static code analysis tools usually require careful integration into the project build process. For large software products, these builds are often somewhat of a black art, involving the use of Make and Ant. There are many options and dependencies. All static code analysis tools offer powerful utilities to analyze the build process and insert themselves into the right places, but some manual tuning is usually required.

5 Queries for Choosing the Right Code Analysis Tool

1. Do you need a static or dynamic analysis tool?
2. What languages and platforms does it support?
3. How flexible is the reporting component?
4. How easy is it to add or update rules?
5. Does it integrate with your IDE?

These tools also must be integrated into developers' daily work. Again, tool makers offer both command-line versions of the tools as well as plug-ins for many of the popular integrated development environments such as Eclipse and Visual Studio.

Most importantly, the tools require that the code base have a subject matter expert (SME) who can also provide the same service for the tools . That person will answer questions not just about how the tool operates but also about the issues that the tool is finding -- including identifying when the tool is generating a false positive. The SME will provide training and support to other developers, a fairly heavy workload for the first few weeks, until everyone is familiar with the static analysis tool. After that, that part of the workload should settle down to several hours a week.

Initial Analysis: Panic Time

The biggest challenges with static code analysis tools are problems in existing code. There's an old programmer's joke that says God made the world in six days because he had no installed base. This is certainly not the case for most businesses, which often have millions of lines of code.

The first time an existing codebase is analyzed, tens of thousands of issues will be found. Don't panic. Remember, these issues have been there for awhile, and the software continues to function and provide users with what they need.

At ACI Worldwide, all the issues from an initial build on existing code are immediately deferred and hidden from sight. That way developers don't get overwhelmed and can stay focused on ensuring that new problems aren't introduced into the code. At some point in the future, product planners and the senior development staff review the deferred issues, prioritize and group them, and decide when remediation can be factored into the planning for a future release. There's no perfect approach, and businesses must always make hard decisions about whether to counter a vulnerability or assume the risk.

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